1. Field of the Invention
The present invention relates to a method for emergency-message broadcasting using vehicular communication based on IEEE 802.11p/WAVE communication standard wherein transmits emergency message information to peripheral vehicle.
A method for emergency-message broadcasting of the present invention can quickly transfer emergency message even when respective vehicles are accessed to different channels during SCH(Service Channel) interval according to multiple channel operation wherein defined by IEEE 1609.4 of WAVE communication standards.
2. Description of the Related Art
Vehicular ad-hoc network is a network system specialized in Mobile Ad-hoc Network structure for vehicle that moves fast on road. Vehicular network system not only supports communication between vehicle and infrastructure but also vehicle to vehicle and transmits safety related application as well as information/entertainment (infotainment) application. By using such vehicle network system, drivers can drive safer by using safety relevant application. Moreover, multi-media services such as media streaming, on-line game, and web-search can be provided.
Such vehicle network system can be regulated under IEEE 802.11p/WAVE (Wireless Access in Vehicular Environments) communication standard. The IEEE 802.11p/WAVE communication standard supports wireless communication system with high velocity, small range and low delay features in vehicle environment of active mobility. For this, WAVE communication standard includes IEEE 802.11p and IEEE 1609 standard. Herein, IEEE 1609.4 which is one of WAVE communication standard defines multiple channel operation for vehicle communication.
Following WAVE technology standard, vehicle communication operates using both methods of Time Division Multiple Access, TDMA and Frequency Division Multiple Access, FDMA.
For TDMA method, WAVE technology standard defines channel switching operation to SCG interval wherein includes CCH (Control Channel) interval and a plurality of SCH (Service Channel) interval. Herein, CCH interval and SCH interval can be formed basically in interval length of 50 ms.
For FDMA method, WAVE technology standard assigns 7 different channels. 7 channels, herein, can comprise 1 CCH and 6 SCH channels. Respective channel bandwidth is 10 MHz and CCH is used to exchange control information which includes a safety message and SCH is used to provide a non-safety message between nodes.
Boundary between TDMA and FDMA of such WAVE communication standard causes problems in transferring emergency messages. For example, when emergency message is generated during SCH interval, the emergency message is stored in queue until it becomes a CCH interval. Such procedure can be very inefficient in emergencies.
In an effort to solve the problem, various methods of transferring emergency message are suggested but, the method of transferring emergency messages only aims to shorten average delay time wherein necessary for transferring emergency messages. Thus, it has a problem of not being able to promptly transfer relevant messages to nearest neighbor vehicle wherein should receive message information regarding emergency event in priority (from the relevant event).